The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
During processing of substrates such as semiconductor wafers, various substrate treatments including deposition, patterning, and/or etching are performed. Substrate processing systems for performing deposition typically include a processing chamber with a pedestal. A substrate such as a semiconductor wafer may be arranged on the pedestal. A process gas mixture including one or more precursor gases may be introduced into the processing chamber to deposit film on the substrate. Plasma may be used to activate chemical reactions.
Etching may be performed in a processing chamber by introducing etch gas mixtures into the processing chamber. Plasma may also be used during etching. During etching, it may be desirable to etch some areas of the substrate while not etching other areas of the substrate. Hardmask film may be deposited and patterned on the substrate prior to etching to prevent etching in certain areas of the substrate under the hardmask film. The hardmask film needs to be hard and dense to withstand the etch process. After etching is performed, the hardmask film needs to be removed by a hardmask removal process that does not damage the substrate.
Amorphous carbon and polysilicon based films may be used as hardmasks for etching high aspect ratio (HAR) features. In VNAND and dynamic random access memory (DRAM) applications, the hardmask film needs to be highly etch selective to dielectric layers underlying the hardmask film. Therefore, the hardmask film should be hard and dense (while balancing ease of removal and etch selectivity) and provide control over modulation of hole etch uniformity.
Metal-doped carbon hardmasks can also be used in advanced memory patterning applications. Metal-doped carbon hardmasks can be used when underlying dielectric layers include silicon dioxide (SiO2) and/or silicon nitride (Si3N4 or SiN). Metal-doped carbon hardmasks may be deposited in a plasma-enhanced chemical vapor deposition (PECVD) chamber using a precursor gas mixture including metal-containing halides (such as fluorides (F) and chlorides (CI)) and hydrocarbon (CxHy) precursor gas, where x and y are integers greater than zero. Hardmask film that is deposited using precursor gas including F or CI species does not bond well to SiO2 or SiN film. Hydroxide (—OH) groups in underlying dielectric layers also do not bond to the metal containing compounds. In addition, F and Cl-based radicals produce volatile compounds that are pumped away during the process.
Several adhesion/interface layers are also being evaluated such as boron carbide (B4C), carbon (C), boron (B), or tungsten silicide (WSi2). These materials provide good adhesion at an interface between the metal-doped carbon hardmask and SiO2 or SiN. However, these materials are different than the substrate (SiO2 or SiN) and the hardmask (metal-doped carbon), which may cause issues when removing the masks after pillar etching is complete or require extra steps to strip an interface layer.